building everything with a set of specific preprocessor token(s)/definition(s)?

[René J.V. Bertin]

Hi,

I'd like to investigate something Qt-related that would require me to build all frameworks with a specific set of preprocessor tokens defined. Rather than patching all toplevel CMake files I'm hoping for way to define those tokens in the cmake invocation, IOW on the cmake command line.
It seems CMake itself doesn't make that easy because of a lack incremental mechanisms, but maybe there's a hook in the ECM that I've overlooked?

Thanks,
René